McMahon, a billionaire and business executive, founded with her husband what is now known as the WWE, World Wrestling Entertainment, Inc.
At the SBA, McMahon has proven to be a workhorse, traveling the country to promote small business and the president's economic agenda while avoiding the scandals that have plagued several of her Cabinet colleagues.
In the statement announcing her resignation, McMahon effusively praised Trump. McMahon's plans were first reported by Politico.
All three positions have so far been filled with acting replacements, not permanent ones.
Reports suggested that Trump had been so pleased with McMahon's efforts that she was once considered as a replacement for Commerce Secretary Wilbur Ross.
The SBA provides support to small businesses through loans and monitors officials' compliance with federal contract laws.
Unlike other cabinet officers who have been scorched by the white-hot light of media scrutiny and Democratic criticism, McMahon has largely avoided negative publicity. She lost two bids for Senate in 2010 and 2012 against her Democrat rivals Sens. "She has much to be proud of and will be missed". She regularly travels around the country to promote the president's agenda, including recent trips to promote the new U.S. -Mexico-Canada trade deal.